Screw hold repair in fabric?

It's annual time on the starduster, and several of the screw holds
to hold on the inspection plates have been enlarged over the years to
the point where a screw won't stay in the whole. Around each inspection
hole, there is a thickened area in the fabric that has been drilled
or punched to recieve the screws. We are using sheet metal screws.
I don't know what covering system was used, but could probably find
out (it was recovered several years before I bought into the
partnetship). Is there some kind of filler that could be placed in
these holes and then drilled out back to a smaller size so that the
screws would stay in?

Thanks in advance for any ideas.

Brian Huffaker, DSWL )
RV-8A 80091 Riviting foward lower fuseage skin
1/4 Starduster Too N23UT flying.